In gas turbine combustors, combustion gas flowing through the inside thereof can cause the wall temperature to exceed the tolerable temperature of its material. To prevent this, a cooling structure is provided. Many examples of such a cooling structure of a gas turbine combustor are known that employ a method of cooling by passing a cooling medium, such as compressed air or steam, to the wall portion.
One such example is the technology described in Patent Document 1. The technology described is a closed air cooling cycle cooling structure wherein, as illustrated in FIGS. 6A to 6E, compressed air supplied from a compressor (not illustrated) is bled from the side upstream of a combustor 100 and this pressurized bled pressurized air Ab is used to cool a wall portion (wall) 101. Thereafter, the bled pressurized air Ab is recovered and reused as combustion air for the combustion of fuel in the combustor 100 together with the main flow of compressed air.
The wall portion 101 of the combustor 100 (specifically a wall portion of a combustor basket) is wall cooled by cooling air being supplied to an internally formed cooling air passage. This wall portion 101 is divided into two regions: a downstream wall region Da closer to the turbine, which is cooled by passing the bled pressurized air Ab as cooling air through a cooling air passage 102A from the downstream side to the upstream side of the combustion gas flow F; and an upstream wall region Ua closer to a burner, which is cooled by passing bled compressed air Ac, which is bled from the main flow of the compressed air flowing through a casing inner space, as cooling air through a cooling air passage 102B to an acoustic liner and a damper 103.
Accordingly, a gas turbine combustor including such a closed air cooling cycle cooling structure is capable of effectively utilizing the compressed air supplied from the compressor, performing wall cooling in the combustor 100 on the side closer to the turbine having relatively high temperatures using the bled pressurized air Ab, and performing wall cooling on the side closer to the burner having relatively low temperatures using the bled compressed air Ac.
As a result, the bled pressurized air Ab that cools the downstream wall region Da of the combustor 100 and the bled compressed air Ac that cools the upstream wall region Ua of the combustor 100 are effectively reused as combustion air. This results in a gas turbine combustor including a cooling structure that is capable of reducing the usage amount of bled pressurized air Ab, which needs to be pressurized, and efficiently cooling the wall of the combustor 100.